1. Field of the Invention
The present invention relates to device and method for controlling supply of current and static capacitance to a compressor.
2. Background of the Related Art
FIG. 1 illustrates a diagram showing a related art device for controlling supply of current and static capacitance to a compressor.
Referring to FIG. 1, a related art device for controlling supply of current and static capacitance to a compressor is provided with a utility power supply 1, a first relay 2 for being turned on/off in response to a control signal from the compressor, a reactor 3 for absorbing a reactive power from the utility power supplied through the utility power supply 1 according to the turning on/off operation of the first relay 2, and providing the utility power to a main winding C1. of a compressor motor xe2x80x98Mxe2x80x99, a second relay 4 for monitoring a voltage on the reactor 3, a first contact 4a connected parallel to the third reactor 3 for being opened or closed by the second relay 4, an operating capacitor 5 connected in parallel to the third reactor 3, a starting capacitor 6 connected in parallel with the operating capacitor 5, a third relay 7 for monitoring a voltage at starting, a second contact 7a fitted to a fore end of the second relay 4 for being opened or closed by the third relay, and a third contact 7b fitted to a rear end of the starting capacitor.
The operation of the foregoing related art device will be explained.
Upon application of the control signal from the compressor, the first relay 2 is turned on, to supply a power to the main winding C1 of the compressor motor xe2x80x98Mxe2x80x99through the third reactor 3. In this instance, the third reactor 3 removes a reactive power from the power to the main winding. On the other hand, the utility power is supplied to a supplementary winding of the compressor motor xe2x80x98Mxe2x80x99through the parallel circuit of the operating capacitor 5 and the starting capacitor 6 as the third contact 7b is closed. Referring to a region 8 in FIG. 1, at an initial starting of the compressor, since the compressor motor xe2x80x98Mxe2x80x99is not rotated, a voltage to the third relay 7 is too low to put the third relay 7 into action. And, if the compressor motor xe2x80x98Mxe2x80x99becomes to rotate at a revolution higher than a preset value as the voltage on the third relay 7 rises according to the rotation of the compressor motor xe2x80x98Mxe2x80x99, the third relay 7 comes into action, to close the second contact 7a and to open the third contact 7b. Since the second relay 4 comes into action as the second contact 7a is closed, the first contact 4a is closed to turn off the third reactor 3 and to open the third contact 7b, to isolate the starting capacitor from the circuit. That is, at the moment of starting, the third reactor 3 becomes to be connected to the compressor motor xe2x80x98Mxe2x80x99in series to limit an excessive current, and the starting capacitor 6 provides a greater capacitance to the supplementary winding C2 to improve starting characteristics of the compressor.
However, the related art device for controlling supply of power to a compressor has the following disadvantages.
First, there have been frequent troubles in the region 8 at which a starting capacitance is controlled.
Second, the mechanical system of the device for supplying power to the compressor costs high.
Third, the starting control by the voltage rise following rotation of the compressor motor xe2x80x98Mxe2x80x99can not define a starting current accurately and has a poor starting characteristic.
Fourth, the generation of excessive current in starting of the compressor actuates the circuit breaker, gives bad influences to peripheral device of the compressor, and has inconvenience in restoring the compressor to an original state.
Accordingly, the present invention is directed to device and method for controlling supply of current and static capacitance to a compressor that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. An object of the present invention is to provide device and method for controlling supply of current and static capacitance to a compressor, which can prevent flow of excessive current to a main winding of the compressor.
Other object of the present invention is to provide device and method for controlling supply of current and static capacitance to a compressor, which can supply a stable voltage to the compressor regardless of variation of an external utility voltage.
Another object of the present invention is to provide device and method for controlling supply of current and static capacitance to a compressor, which can prevent internal contacts suffer from damage caused by sharp current concentration during starting and operation of the compressor.
Further object of the present invention is to provide device and method for controlling supply of current and static capacitance to a compressor, which can make stable supply of current and static capacitance to the compressor to be consistent to an external temperature and season.
Still further object of the present invention is to provide device and method for controlling supply of current and static capacitance to a compressor, which can improve starting characteristics of the compressor.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the device for controlling supply of current and static capacitance to a compressor includes a control signal generating part for providing a control signal for controlling a current and a static capacitance provided to the compressor different in starting and after the starting, a current controlling part for limiting a current of a utility voltage in supplying the current to a main winding in starting and releasing the limiting after the starting by changing an internal circuit in response to the control signal, and a static capacitance controlling part for supplying a starting static capacitance and an operative static capacitance from the current of the utility voltage to a supplementary winding in starting, and the operative static capacitance after the starting by the change of the internal circuit in response to the control signal.
In another aspect of the present invention, there is provided a method for controlling supply of current to a compressor, including the steps of (a) limiting a current of a utility voltage in supplying the current to a main winding during starting the compressor, and releasing the limiting after the starting, and (b) providing a starting static capacitance and an operative static capacitance form the current to a supplementary winding during the starting of the compressor, and the operative static capacitance after the starting.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.